Paper towel dispenser

ABSTRACT

A powered dispenser for dispensing individual paper towel segments from a continuous roll of paper provided with spaced lines of tearing comprises a housing, a support for the roll of paper, a feed mechanism, and a control device. The control device senses the presence of a user to activate the feed mechanism, controls the amount of material which is dispensed from the housing for any one cycle, and prevents further dispensing of the paper until the previous segment is separated from the roll. The control device detects the leading edge of the paper to initiate monitoring of the length of paper to be dispensed to prevent any cumulative error in dispensing the segments.

TECHNICAL FIELD

[0001] The present invention generally relates to paper towel dispensersand, more particularly, to a non-touch paper towel dispenser fordispensing a web of material from a roll.

BACKGROUND OF THE INVENTION

[0002] Dispensers for toweling have primarily been designed to dispensea continuous length of web material, folded paper towels, or rolls ofpaper towels. Continuous towels are generally made of a reusablematerial and form a towel loop outside of the dispenser cabinet for theconsumer to use. Folded towels are paper towels which are pre-cut andfolded into various configurations to be individually dispensed for use.Roll towels are continuous rolls of paper toweling which are woundaround a central core and which are, upon dispensing, separated into anddelivered as individual lengths of material.

[0003] Continuous web dispensers, such as those disclosed in U.S. Pat.No. 2,930,663 to Weiss and U.S. Pat. No. 3,858,951 to Rasmussen, requirethe user to pull on the loop of exposed toweling in order to cause alength of clean toweling to be dispensed and the exposed soiled towelingto be correspondingly taken up within the dispenser. Althougheconomical, the continuous exposure of the soiled toweling is deemedunsightly and, therefore, unacceptable to many consumers when comparedto the many available alternatives. Further, the exposure and possiblereuse of soiled toweling may present additional health hazards andsanitation concerns which should be avoided.

[0004] The use of interfolded paper towels or C-fold paper towelseliminates the potential health risks associated with continuous webtoweling. For instance, dispensers for folded paper towels, such asdisclosed in U.S. Pat. No. 3,269,592 to Slye et al., allow a user todispense the towels by pulling on the exposed end of each new individualtowel. These dispensers are also easy to refill with folded towels.However, a number of the folded towels will sometimes drop out of thelower opening of the dispenser when only the exposed towel is pulled,especially when the stack of towels in the dispenser is small. This canresult in a significant waste of paper towels. Accordingly, foldedtowels are not as economical as other kinds of alternative dispensers.

[0005] Roll towels are cheaper to manufacture and produce less wastethan folded towels. Roll towels also eliminate the potential health andsanitation problems associated with continuous web toweling systems.Dispensers for roll towels may include a lever, crank, or otheruser-activated mechanism for dispensing a length of towel, and a bladefor severing the length of towel from the remaining roll. However, ascan be appreciated, manual contact with a dispensing lever or the likeraises health concerns for the user. To alleviate these health concerns,dispensers, such as U.S. Pat. No. 4,712,461 to Rasmussen, eliminatecontact with any part of the dispenser, and instead rely upon the userdirectly pulling the paper towel out of the dispenser. As a result, thepaper towel must be provided with sufficient strength to effect rotationof the feed roller and actuation of the blade without premature tearing.Paper possessing the requisite strength to operate the dispenser islimited in the amount of softness and absorbency which can be providedto the paper towels.

[0006] Dispensers for roll towels have also been electrically powered.As shown in U.S. Pat. No. 5,452,832 to Niada, a light sensitive deviceis used to detect the presence of a user's hand in front of thedispenser and advance the toweling for a predetermined length of time.The dispensed length of paper towel is then separated from thecontinuous web by pulling the paper against a serrated cutting member.While the feed roller is powered, the cutting action still requires thepaper to possess a certain minimum strength and generally produces arough, unsightly cut.

[0007] U.S. Pat. No. 4,738,176 to Cassia discloses an electricallypowered dispenser which also includes a reciprocating cutter to producean individual towel from the continuous web of paper. While thisarrangement enables the use of softer and more absorbent paper, thedispenser requires a substantial amount of energy to drive the feedmechanism and the reciprocating cutter. Accordingly, the batteries mustbe replaced much more frequently. Moreover, the system is more complexand costly with its use of one-way clutches.

[0008] Also, in some electrically powered dispensers, such as U.S. Pat.No. 4,796,825 to Hawkins, the paper will continually dispense while ahand or other object is placed in front of the sensor. Hence, thedispenser is subject to easy abuse and waste of paper. Moreover, somedispensers are subject to dispensing paper by the general proximity of aperson irrespective of whether a paper towel is needed. In an effort toavoid abuses, some dispensers, such as U.S. Pat. No. 4,666,099 toHoffman, have incorporated a waiting period where the dispenser will notoperate for a brief time after each use. However, the need to wait canbe frustrating to users under some circumstances.

SUMMARY OF THE INVENTION

[0009] The present invention is directed to an electrically powereddispenser which overcomes the disadvantages of the prior art.

[0010] In one aspect of the present invention, the dispenser facilitatesthe dispensing of a roll of paper with spaced apart transverse lines oftearing (e.g. perforation lines) for easily separating individual sheetsfrom the continuous roll without cutting. As a result, paper with a highdegree of softness and absorbency can be used without the high energydemands required by a reciprocating cutter.

[0011] In another aspect of the invention, the dispenser senses theleading edge of the continuous web of paper material to initiate acontrol device which controls the length of each segment of paper. Inthis way, the dispenser can always place the transverse tearing line atthe proper position in relation to the discharge opening for eachdispensed sheet, irrespective of variations of the spacing for thetearing lines within a tolerance range.

[0012] In another aspect of the invention, the dispenser includes asensor for sensing the presence of a sheet which has been dispensed, butnot removed, in order to prevent the dispenser from dispensing any moresheets until the previous sheet has been torn off. In this way, abuse ofthe dispenser and waste of the paper material can be minimized withoutrequiring the use of a waiting period wherein the dispenser will notoperate. Accordingly, the dispenser is always ready for use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a side diagrammatic view of the dispenser of the presentinvention with the cover in a closed position and showing a sheetsegment of a web being dispensed.

[0014]FIGS. 2 and 3 are flow diagrams showing flow control for operatinga dispenser according to embodiments of the invention;

[0015]FIG. 3a is a portion of a routine for dealing with alarmconditions in the control flow shown in FIG. 3.

[0016] FIGS. 4 is a block diagram showing control elements forcontrolling a towel feeder according to embodiments of the invention.

[0017]FIGS. 5 and 6 are flow diagrams showing alternative jam clearingmethods consistent otherwise with the control flow of FIGS. 3 and 3a.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] Referring to FIGS. 1 and 4, a non-touch paper towel dispenser 10according to the present invention comprises a chassis 12 which includesa back panel 14, side panels 16, and a pivotal front cover 20 attachedby a pin, hinge, or other conventional attachment mechanism 20 a (FIG.1). Front cover 20 is opened to permit loading of a roll of papermaterial 25 into dispenser 10. The roll 25 consists of a continuous webof paper 27 wound upon a hollow, cylindrical core (not shown). In thepreferred embodiment, the web 27 includes a series of spaced apart,transverse tear lines to subdivide the web into sheet segments 42 of apredetermined length. Roll 25 is rotatably supported a pair of arms 35extending forwardly from back panel 14. Each of the arms includesinwardly directed hub 35′ loosely received within the core 38′ of theroll 25 to permit free rotation of the roll 25. Nevertheless, othermounting arrangements could be used.

[0019] A feed mechanism 37 is mounted within the housing defined bychassis 12 to dispense the web 27 in incremental sheet segments 42. Inthe preferred construction, feed mechanism 37 includes a feed roller 22and a pressure roller 24. Feed roller 22 and pressure roller 24 aremounted upon axles 45, 46, respectively, rotatably supported by sidepanels 16, 18. The pressure roller 24 is preferably biased against thefeed roller by a spring (not shown) to define a feed nip 47 fordispensing the web 27 through a discharge opening 48. The dischargeopening includes a towel sensor 38 as described below.

[0020] In use, feed roller 22 is driven by an electric motor 30 mountedwithin the dispenser. Specifically, a worm gear 52 is secured to driveshaft 54 of motor 30 to engage a drive gear 56 secured to axle 45 androtate feed roller 22. When the paper web 27 is fed into nip 47,rotation of the feed roller (counter clockwise as viewed in FIG. 1)causes the web to be advanced around feed roller 22, through dischargeopening 48. A guide plate 87 is provided to direct the web along thedesired path. Low power requirements insure that the batteries 58 needonly infrequent replacement. Other feed mechanisms having other rollerand gear arrangements, or other power supplies, such as a step down ACto D.C. power supply, could be used.

[0021] When a roll 25 is loaded into dispenser 10, the leading edge 36of web 27 is manually fed rearward between feed roller 22 and pressureroller 24. When front cover 20 is closed, a loading switch (not shown)may be engaged to activate motor 30 and automatically drive feed roller22 in a direction (i.e. counter-clockwise as viewed in FIG. 1) toadvance web 27 around feed roller 22 and to discharge opening 48.Alternatively, as described in the control embodiment of FIG. 2, acustodian can set up the roll 25 and web 27 such that the leading edge36 is downstream of the sheet sensor 38. When cover closure is detected,the motor 30 will run in reverse to bring the leading edge 36 upstreamof the sheet sensor 38 and then stopped (See discussion of FIG. 2,below, for further explanation). The custodian can use a forward andreverse jog switch 92 to position the leading edge where desired. Whilethe loading switch is preferably actuated automatically upon closing ofthe cover, it could be manually actuated if desired. The leading edge 36of the web material is advanced until detected by towel sensor 38positioned in discharge opening 48. The towel sensor 38 is coupled witha microprocessor 53 or the like so that once the leading edge has beendetected by sensor 38, motor 30 is reversed until the leading edge 36 ofweb 27 is clear of the range of sensor 38. This position places theleading edge 36 between the feed roller 22 and sensor 38. The towelsensor 38 may be any suitable mechanism, for example, a limit switch(not shown), an acoustical sensor (not shown), or an optical sensor 38that includes an emitter and a photo diode that is occulted by theleading edge 36 of the web. In the latter example, the emitter may bepulsed and the output of the photodiode high-pass filtered. In this waythe effect of ambient light on the photodiode is compensated. This maybe implemented directly through microprocessor 53.

[0022] The present invention is preferably used for dispensing webmaterial with spaced apart tearing lines, such as prescored lines ofperforation, resulting in sheet segments 42 of, for example, nine inchesin length. Of course other lengths could be used depending on designerpreference. By using a preperforated web material, the sheet segmentscan be easily separated from the web without requiring cutting of theweb. The perforation tensile strength is light enough such that the webmaterial can be easily separated in a smooth edge or some other desiredor appealing edge. By avoiding the need for a cutter, energy may beconserved because the motor needs only to rotate the feed roller.Because the web 27 is power fed, minimum strength is required of theweb. The web does not need to have sufficient strength to draw outadditional portions as a leading portion is removed as in dispensersthat require the web to be pulled out manually. Thus, the paper materialof which the web is made can be soft and highly absorbent.

[0023] Dispenser 10 further includes a proximity sensor 40 that detectsthe presence of a user's hands or the like as the hand or hands approachthe front of the dispenser 10. Sensor 40 may be any kind of suitableproximity sensor or switch. For hands free operation, sensor 40 may be aproximity sensor. A Proximity sensor 40 is coupled with microprocessor53 to activate motor 30 when a hand is detected so as to drive feedroller 22 and thereby dispense a predetermined length of the webmaterial. The dispensed web exits through discharge opening 48, in orderto be easily accessible to the user. The user then grasps the dispensedsheet segment 42 of web material and tears off the desired length ofmaterial along a prescored perforation line 72 (see FIG. 1). The leadingedge 36 of the next sheet segment 42 a is positioned between towelsensor 38 and feed roller 22. If the user dispenses, but does notseparate it from the web, the towel sensor 38 detects the presence ofthe segment 42 a. As long as sheet segment 29 a is detected by sensor38, the microprocessor will prevent further activation of motor 30. Thisdiscourages abuse of the dispenser and waste of the paper. Also, whilethe towel sensor 38 is described as a single, centrally positionedsensor in discharge opening 48, a pair of spaced towel sensors (notshown) could also be provided. In this case, even if the leading towelsegment is irregularly torn, apart from the tearing line, only one towelsensor need be uncovered to enable activation of the motor.

[0024] As explained further below, dispenser 10 feeds a single sheetsegment 42 of web 27 after detecting that a previously fed sheet segmenthas been separated from the web 27. To control the amount of web 27 fedso that one sheet segment only is fed, dispenser 10 employs a lengthdetector 48 which establishes the amount of web fed during eachdispensing cycle each time the motor is activated. The length detector48 may be, for example, an encoder, either electromechanical or optical,that outputs a pulse for each increment of web dispensed. The lengthdetector 48 may be coupled to microprocessor 53 and employed incontrolling the dispenser 10 as discussed below. Another alternative toencoding successive incremental displacements of the web 27 is to detectthe difference in transmissivity of the web when a perforation linecrosses an optical interrupter. That is, an emitter-photodiodecombination may be used to provide a signal that indicates a first levelof light reception as web is fed and when the perforation crosses thelight path. A pulse may be generated by the presence of the perforationsthrough the web. The microprocessor 53 may count the pulses generated bythe length detector 48 where an encoder embodiment is employed todispense the proper amount of web material. For instance, when thetearing lines are nine inches apart, the microprocessor counts thecorresponding number of pulses to dispense nine inches of the web 27.While a dispenser is preferably set to dispense a roll with sheetsegments (or a multiple of sheet segments) of a predetermined length, aswitch, dial, button or other means could be used to adjust the lengthof the dispensing cycle to meet different kinds of rolls. Also, othercontrol devices could be used, including other counting arrangements ora timer device. Note that in the encoder embodiments of length detector48, as discussed below, cumulative error does not occur becausecumulation of incremental lengths does not begin until the leading edge36 is detected. Thus error can only accumulate over the span of a singlesheet segment 42.

[0025] If a user pulls on the leading edge of the sheet segment beingdispensed before the cycle has been completed, the motor 30 may stalldue to the increased load placed on the worm gear 52. The web 27 may beprevented from slipping about feed roller 22 when pulled because of thebraking characteristic of the worm gear and the pinching engagement ofthe feed nip 47. When the motor stalls, the microprocessor 53 may storethe cumulative displacement and reactivate the motor to dispense theremaining portion of the sheet segment after a short pause (See FIG. 6and attending discussion, below). Alternatively, the motor may bereversed so that the sheet segment is pulled upstream of the towelsensor 38 and fed forward again to register the portion of the leadingedge again in preparation for a new dispensing cycle.

[0026] Referring to FIG. 2, control flow for embodiments of toweldispenser 10 may begin with the detection of an open cover or towelrequest at step S100. If a sheet request is made, control proceeds tostep S105 where it is determined if a towel is present, that is, if apreviously fed towel has not been torn off. If a towel is present,control returns to step S100 otherwise it proceeds to step S120 wherethe feed motor 30 is started in the forward feed direction. The feedmotor 30 continues until in step S130, the leading edge of the towel isdetected at which point, the length (displacement) detector 48 isinitialized in step S140 so that the total displacement of the web 27can be detected. The web 27 is advanced for the predefined displacementto expose one full towel sheet segment 42 in step S150 as indicated bythe length detector 48. Next, in step S160, an exposure timer isinitialized. Next, at step S170 optical sensor 38 is polled to determineif a towel has been removed within the duration of the exposure timer.If not, control loops until the exposure timer times out at step S180.If the towel is removed before the exposure timer times out, controlreturns to step S100. If the exposure timer times out in step S180,control proceeds to step S190 where the feed motor 30 is reversed todraw the towel back inside the dispenser 10. In step S190, the reversefeed continues for a short first interval to draw the leading edge backpast the towel sensor 38. If the towel edge was not detected due to someerror in step S195, an alarm is set at step S10 and control proceeds tostep S10. If the towel edge 36 is successfully detected (Step S190 mayinclude a timer operation so that the program may wait for apredetermined period of time before proceeding to step S195), controlreturns to step S100. If a cover-open condition is detected in stepS100, control also proceeds to step S10. The program pauses at step S30until a cover closure is detected at step S30, whereupon controlproceeds to step S90. In step S90, the feed motor 30 is reversed in anoperation as in step S190. Then control returns to step S100 where thedispenser 10 waits for another sheet request.

[0027] Referring to FIG. 3, an alternative control flow begins when thedispenser is reset (either power on or pressing a reset button 91′)whereupon control begins at step S205. In step S205, the processor 53waits for a sheet request. As discussed above, this request may be madeby a proximity sensor in one embodiment, or by some other type of switchor indicator. When a sheet request is made, control passes to step S210where the sheet detector 38 is polled to determine if a sheet segment isstill present having been ejected previously and not torn off. At stepS220, if a sheet is detected, control returns to step S205. If the sheetis not detected, the feeder motor is started in step S225 and a watchdogtimer initiated. Then in step S235, the sheet detector is polled and atstep S240 if the sheet is detected, control proceeds to step S245. Ifthe sheet is not detected, control loops back through steps S230 to S235until the watchdog timer times out in step S230 whereupon controlbranches to step S250 in which an alarm is set and the motor stopped towait for reset.

[0028] Note that in step S235, the presence of the sheet is anindication of the leading edge of the web. Therefore, in step S245, theencoder pulse detector of the encoder embodiment (length detector 48) iszeroed and control flows to step S280. In step S280, another watchdogtimer is started and the processor waits for each encoder pulses bylooping through steps S285 and S260. If the watchdog timer times outbetween pulses, control branches out of this loop to step S255. Eachtime a pulse is detected, control flows to step S290 where the pulsecounter is checked against the cumulative count of pulses thus far. Ifthe cumulative count is short of the number corresponding to a fullsheet, control returns to step S280. If all the pulses are cumulatedthrough the S280, S285, S290 loop, control proceeds to step S295 wherethe motor is stopped. Control then returns to step S205.

[0029] If the watchdog timer in step S260 times out, control proceeds tostep S255 where the feed motor 30 is reversed and another watchdog timeris initiated. The sheet detector is polled and control loops throughsteps S265 and S275 until either the watchdog timer times out or theedge is detected. If the edge is detected the feed motor continues inreverse for a short interval to bring the sheet edge upstream of theoptical sensor (sheet detector) in step S270. Then control proceeds tostep S225. If the watchdog timer times out in step S275, controlproceeds to step S250.

[0030] Note that in either of the above control embodiments or anyothers (FIGS. 2 or 3), a routine may be included to insure prevention ofmore than a predefined number of sheets from being dispensed within aspecified time interval. If more than this predefined number of requestsis made, the controller may be programmed to ignore the request untilthe lapse of a timer. So, for example, if more than three requests aremade in a 10 second period, the processor can wait until the expirationof the ten second interval or for the expiration of a new 10 secondinterval after the third request. This is an abuse deterrent.

[0031] Note that discharge opening 48 defines an access that is narrowenough to prevent a user's fingers from reaching the leading edge 36 ofthe web 27 when the dispenser 10 is waiting for a request for a newpaper sheet segment. The towel sensor 38 is located between the accessdefined by the discharge opening 48 and the blind end defined by afeedthrough between feed roller 22 and an arcuate guide plate 87. Withthis arrangement, the towel sensor is hidden from interference byambient light. Also, the perforation line 72 is located downstream ofthe blind end so that a sheet segment 42 can be torn away from the web27. The perforation line 72 is above the towel sensor 38 when thedispenser 10 is waiting for a request. In this way the towel sensor 38registers the position of the leading edge 36 shortly after the motor 30starts feeding forward.

[0032] The control flow starting with step S255 is for the purposeclearing a jam. Referring to FIG. 5, an alternative way of dealing withthe timeout in step S260 of the watchdog timer begins at step S355 wherethe feed motor 30 is reversed. Control loops through step S365, untilthe encoder pulses are cumulated for a short number of counts, perhapsonly one or two. Thus, the feed motor is reversed for only a shortinterval of reverse displacement. The count of the forward feedoperation is then adjusted in step S370 and the feed-forward operationresumed at step S280. Thus, if two backward pulses are used for thiscorrection, the cumulative count employed in step S290 would bedecremented by two to make up the difference.

[0033] Another alternative way to deal with a jam is to simply pause theforward feed operation. Referring to FIG. 6, in step S455, the feedmotor 30 is stopped and a delay timer initiated. Control loops throughstep S465 until the delay timer times out and the feed motor isrestarted in step S470. After that control returns to step S280.

[0034] Referring to FIG. 4, a block diagram showing the various sensorsand controls that may be connected to microprocessor 53, according tothe various embodiments discussed above, is shown.

[0035] It will be obvious to one of ordinary skill in the art thatnumerous modifications may be made without departing from the truespirit and scope of the present invention, which is to be limited onlyby the appended claims.

1. A dispenser for flexible sheet material comprising: a support forrotatably supporting a roll of sheet material; a feed mechanism foradvancing the sheet material; a motor for driving the feed mechanism; acontrol device for powering said motor to drive said feed mechanism soas to dispense a predetermined length of the sheet material; and asensor for detecting a leading edge of said sheet material andactivating said control device.
 2. The dispenser of claim 1 , whereinsaid feed mechanism includes a feed roller driven by said motor and anopposing pressure roller between which the sheet material is passed. 3.The dispenser of claim 2 , wherein said feed mechanism further includesa drive gear and a rotatable axle to support said feed roller and saiddrive gear, and said motor is provided a worm gear engaged with saiddrive gear.
 4. The dispenser of claim 2 , wherein said control deviceincludes an encoder for determining the predetermined length of sheetmaterial.
 5. The dispenser of claim 2 further comprising a housing witha discharge opening, said support and said feed mechanism being withinsaid housing.
 6. The dispenser of claim 5 , wherein said sensor ispositioned between said feed roller and said discharge opening.
 7. Thedispenser of claim 1 further comprising a housing with a dischargeopening, said support and said feed mechanism being within said housing.8. The dispenser of claim 1 , wherein said sensor is a photo-detectordevice.
 9. The dispenser of claim 1 , wherein said control deviceincludes a counter device.
 10. The dispenser of claim 1 , wherein saidcontrol devices includes a timer device.
 11. The dispenser of claim 1 ,further comprising an activation sensor for sensing the presence of auser and activating said motor.
 12. The dispenser of claim 11 , furthercomprising means for preventing activation of said motor when saidsensor detects a dispensed but unremoved segment of the sheet material.13. The dispenser of claim 1 , further comprising means for preventingactivation of said motor when said sensor detects a dispensed butunremoved segment of the sheet material.
 14. A dispenser for flexiblesheet material comprising: a feed mechanism for dispensing a firstsegment of the sheet material; a sensor for sensing the presence of auser, said sensor activating said feed mechanism for advancing the webof sheet material in response to sensing the user; and a controller forpreventing said feed mechanism from dispensing a second segment of thesheet material through said discharge opening until the first segment ofsheet material has been removed.
 15. The dispenser of claim 14 , whereinsaid controller includes a sensor for sensing the presence of the firstsegment of the sheet material when dispensed but not removed.
 16. Thedispenser of claim 14 , wherein said activating sensor includes a lightsensitive sensor.
 17. The dispenser of claim 14 , wherein said feedmechanism includes a motor.
 18. The dispenser of claim 17 , wherein saidcontroller includes a device for controlling the length of the firstsegment of the sheet material, said control device terminating theactuation of said motor when a predetermined length of sheet materialhas been dispensed.
 19. The dispenser of claim 12 further comprising ahousing with a discharge opening, said support and said feed mechanismbeing within said housing.
 20. The dispenser of claim 14 , wherein saidfeed mechanism includes at least one feed roller to dispense to thesheet material and a motor to drive said feed roller.
 21. A dispenserfor dispensing sheets defined by perforations in a roll of paper heldthereby, said dispenser comprising: a motorized feed mechanism with anoutput end from which a leading end of said roll of paper is fed to makeat least one of said sheets accessible to allow said user to remove saidat least one of said sheets from a remainder of said roll; a controllerconnected to control said feed mechanism and configured to feed said atleast one of said sheets responsively to an input generatable by saiduser; a sheet detector connected to said controller and configured toindicate whether a fed one of said at least one of said sheets isremoved from said remainder of said roll; said controller being furtherconfigured to retract said at least one of said sheets after a lapse ofa predefined interval and responsively to said sheet detector.
 22. Adispenser as in claim 21 , wherein said sheet detector is positioned todetect a presence of said at least one of said sheets adjacent saidoutput end.
 23. A dispenser as in claim 21 , wherein: said dispenser hasa housing with an opening at said output end, said opening having ablind end and an access, said access being sufficiently narrow toprevent manual access by said user therethrough; said controller isconfigured to feed one of said sheets for each of said inputs andfurther configured to feed just enough of said roll, such that aperforation line separating said one of said sheets is held, after offeeding of said feed mechanism, between said access and said blind end,whereby, when said one of said sheets is separated from said remainderat said perforation line, a new leading end defined as a result, isguarded against access by said user until a new input by said user. 24.A dispenser for dispensing sheets defined by perforations in a roll ofpaper held thereby, said dispenser comprising: a housing with anopening, said opening having a blind end and an access, said accessbeing sufficiently narrow to prevent manual access by a usertherethrough; a motorized feed mechanism with an output end from which aleading end of said roll of paper is fed to make at least one of saidsheets accessible to allow said user to tear said at least one of saidsheets from a remainder of said roll; a controller connected to controlsaid feed mechanism and configured to feed said at least one of saidsheets responsively to an input generatable by said user; saidcontroller being further configured to stop said feed mechanism at apoint at which said perforation line is held between said access andsaid blind end, whereby, when said one of said sheets is separated fromsaid remainder at said perforation line, a new leading end defined as aresult, is guarded against access by said user until a new input by saiduser.
 25. A dispenser as in claim 24 , wherein: said controller includesa paper leading edge detector between said access and said blind end;said controller including a displacement encoder connected to said feedmechanism to detect successive increments of a feeding of said paper bysaid feed mechanism; said leading edge detector being positioned suchthat a detection of said leading edge after said feed motor is startedand a continued running of said feed motor subsequent to said detectionfor a predefined number of said increments is effective to position newleading edge at said point.
 26. A dispenser for dispensing sheetsdefined by perforations in a roll of paper held thereby, said dispensercomprising: a motorized feed mechanism with an output end from which aleading end of said roll of paper is fed to make at least one of saidsheets accessible to allow said user to tear said at least one of saidsheets from a remainder of said roll; a controller connected to controlsaid feed mechanism and configured to feed said at least one of saidsheets responsively to an input generatable by said user; saidcontroller including a plurality of paper leading edge detectors; saidcontroller including a displacement encoder connected to said feedmechanism to detect successive increments of a feeding of said paper bysaid feed mechanism; said leading edge detectors being positioned suchthat a detection of said leading edge by at least one of said leadingedge detectors after said feed motor is started and a continued runningof said feed motor subsequent to said detection for a predefined numberof said increments is effective to position new leading edge at saidpoint, whereby said leading edge is detected even if said leading edgeis not defined by a contour of said perforation.
 27. A method ofdispensing a flexible sheet material having spaced apart, transversetearing lines from a dispenser, said method comprising: activating amotor to advance a predetermined length of the sheet material from adispenser; sensing the leading edge of the advancing sheet material tocontrol the amount of sheet material to be dispensed; and tearing aleading segment of the sheet material along one of the tearing lines.28. The method of claim 27 , further comprising preventing the advancingof additional sheet material until the advanced segment of sheetmaterial has been torn off.
 29. The method of claim 27 , wherein saidmotor is activated by sensing the presence of a user.
 30. A method ofdispensing a flexible sheet material comprising sensing the presence ofa user, activating a motor to advance a first segment of a sheetmaterial from a dispenser when the presence of a user is sensed, andpreventing further advancement of the sheet material until said firstsegment is removed from the sheet material.
 31. The method of claim 30 ,further comprising sensing of the first segment when dispensed but notremoved from the sheet material.
 32. The method of claim 30 , furthercomprising sensing a leading edge of the advancing first segment anddispensing a predetermined amount of sheet material from said sensing ofthe leading edge.
 33. A method of controlling a powered towel dispenserthat feeds separate sheets defined by perforations in a roll of towelmaterial held by said dispenser, said method comprising the steps of:detecting a request for a sheet of said towel; power-feeding said towelmaterial from said roll responsively to said step of detecting;detecting a leading edge of said towel material and triggering acounting of counting successive incremental feedings of said towelmaterial by an encoder responsively to second step of detecting andterminating said power-feeding when said a count resulting from saidcounting reaches a predefined value, said predefined value beingeffective to dispense a single one of said separate sheets.
 34. A methodas in claim 33 , further comprising the steps of pausing after said stepof terminating and reversing said power-feeding after a lapse of apredefined interval of time where by said single one of said separatesheets is withdrawn into said dispenser.